Sinapis alba

probably better know as White Mustard.
Used as green manure a lot in our area. It is nice to see green fields with 50-70 cm high plants, and on top of them yellow flowers. And this end of November, with freezing nights.
Thanks to BikerBear for hosting the Flower Friday challenge.

The extra is an autumn picture, taken in the Gersprenz, with a lot of sun.